Vehicle management computer

ABSTRACT

A method of and apparatus for starting and accelerating a vehicle through a range of vehicle speeds during which the vehicle internal combustion engine is operated in a plurality of different operating modes is disclosed. Different operating modes are available during normal operation. Under high demand conditions, the engine may be run as a conventional inefficient but effective throttled engine or converted to operation in a fourth mode as a two-stroke cycle engine. The vehicle management system includes a first read only memory for storing a fixed table of engine operating parameters corresponding to various engine conditions, and a random access second storage means for storing a table of engine operating parameters corresponding to various engine conditions with the second table being initially the same as the first table. The system responds to sensed engine conditions to modify the parameters in the second table and controls the vehicle in accordance with the parameters stored in the second table. Both short term modification to accommodate dynamic changes in the sensed engine conditions and long term modification to compensate for relatively slow changes in the engine and the management system are made to the information in the random access memory. The modifications may be on an overall engine basis or an individual cylinder basis.

This is a divisional of U.S. patent application Ser. No. 07/521,500,filed May 10, 1990, now U.S. Pat. No. 5,123,397, which is a divisionalof U.S. patent application Ser. No. 07/226,418, filed Jul. 29, 1988, nowU.S. Pat. No. 4,945,870.

SUMMARY OF THE INVENTION

The present invention relates generally to computer management of theoverall operation of a vehicle and more particularly to a system forcontrolling the operating parameters of the vehicle's spark ignitedinternal combustion engine and in compression ignition engines includingignition timing, fuel, air intake and intake and exhaust valve openingand closing, all interdependently controlled to achieve optimum overallvehicle performance.

Internal combustion engine valves are almost universally of a poppettype which are spring loaded toward a valve-closed position and openedagainst that spring bias by a cam on a rotating cam shaft with the camshaft being synchronized with the engine crankshaft to achieve openingand closing at fixed preferred times in the engine cycle. This fixedtiming is a compromise between the valve timing best suited for highengine speed and the timing best suited to lower speeds or engine idlingspeed.

The prior art has recognized numerous advantages which might be achievedby replacing such cam actuated valve arrangements with other types ofvalve opening mechanism which could be controlled in their opening andclosing as a function of engine speed as well as engine crankshaftangular position or other engine parameters. For example, U.S. Pat. No.4,009,695 discloses hydraulically actuated valves in turn controlled byspool valves which are themselves controlled by a dashboard computerwhich monitors a number of engine operating parameters. This patentreferences many advantages which could be achieved by such independentvalve control, but is not, due to its relatively slow acting hydraulicnature, capable of achieving these advantages. The patented arrangementattempts to control the valves on a real time basis so that the overallsystem is one with feedback and subject to the associated oscillatorybehavior.

In U.S. Pat. Nos. 4,736,724 and 4,730,594 a number of engine performanceindicators are monitored for the purpose of controlling the fuel-airmixture supplied to the engine. In U.S. Pat. No. 4,730,590 a number ofengine performance indicators are monitored and a look-up table isemployed for the purpose of controlling the fuel-air mixture supplied tothe engine. In U.S. Pat. No. 4,782,126 a number of engine performanceindicators are monitored for the purpose of controlling the width of apulse supplied to fuel injectors thereby determining the fuel-airmixture supplied to the engine.

From the forgoing, it is apparent that fuel and ignition are relativelywell managed on the present day automotive engine, however, the openingand closing of the intake and exhaust valves are not. The design ofpresent conventional cam operated engine valves is the result of anensemble of trade-offs. The various approaches of operating the valvegear with different types of cam mechanisms, that allow some control ofthe valves, leave much to desire in engine performance improvementbecause of the limited performance in the area of controlling the valveposition versus time history and the resulting throttling of the valveport due to that history. Because of these facts, the volumetricefficiency is peaked in a narrow region of the required engine operatingenvelope. The result is that the fixed cam engines suffer when startingdue to poor volumetric efficiency, do not idle smoothly at fuelconserving low engine speeds due to the intake valve closing somewhatafter bottom dead center, do not idle without enriched combustionmixtures because of the reverse flow of exhaust to the intake manifolddue to intake-exhaust valve overlap, do not idle well enough to allowusing less than the full complement of cylinders, and provide lesstorque than is possible throughout most of the engine's operation rangedue in a large measure to improper valve timing. The engines run best atthe unique point where the cam gives its best volumetric efficiencyusing mass flow effects that are less than what is possible due to thethrottling effects of slowly opening and closing valves and hence themass flow effects are, in themselves, largely uncontrolled.Additionally, at the high RPM range, these engines suffer from reducedperformance and valve gear jeopardy due to high valve seating velocitiesand approaching valve float. Because of the fact that the valve openingand closing rates vary directly with engine RPM, the valve gear springsoperate in a region where they put the safe long life operation of thesystem in jeopardy due to their being in a transition between being alumped parameter and a distributed parameter element.

In the present fixed cam operated valve engines, the brake specific fuelconsumption curve drops to a minimum as the air to fuel ratio goes fromthe best power point through stoichiometric to the best efficiencypoint. It then starts rising and the engine performance drops off andbecomes unstable at the "lean burn limit." This rise and instability areprimarily caused by the decreased burning rate, incomplete burning, andvariability, and ultimately lack cf, appropriate ignition for flamepropagation throughout the volume of interest. The present cam operatedvalves require valve overlap in order to attain high volumetricefficiency. This valve overlap causes exhaust gas dilution of the chargeat low engine RPM. The dilution of the charge by exhaust gas transfer,in turn, reduces the lean burn limit reduces the

The decreased over-all burning propensity of lean burns causes thepressure versus crank shaft angle to rise more slowly and, with theeffects of required turbulence for less burning time, with greatervariance, peaking later and it may fall to such a low value during theexpansion stroke that the burning may be quenched or, if not quenched,vented to the exhaust while still burning. These problems can besomewhat alleviated by operating the engine at a lower RPM; however, atlower RPM the turbulence of the combusting gasses is lower causing areduction in the burning rate, hence, lower RPM assists the situationonly to a limited extent. Another choice is to advance the ignitionpoint thereby moving the ignition and burning process back relative tothe crank angle. This also assists the situation; however, advancing theignition point causes the ignition point to occur when the peakpressure, temperature and turbulence are less and less optimum forignition to take place causing longer ignition delays with increasedprobability of flame quenching taking place, in turn causing variableignition timing, misfires and generally increased variance of thepressure as a function of time in the combustion chamber. These problemslimit the extent to which the brake specific fuel consumption will fallat higher air to fuel ratios. If these problems were solved, the brakespecific fuel consumption and the emission would fall until the air tofuel ratio reached such high values that entropy would grow to such alevel where the thermal efficiency would become the dominant limitingfactor.

The ignition of the fuel-air charge can be effected by controlling theturbulence, temperature and pressure at the time of ignition along withan ignition source that can establish and maintain an ignition arc underthese conditions. Highly turbulent conditions of the charge may blow outan ignition arc. When an induction ignition source is used, it must havesufficient potential to break down the spark plug gap and sufficientenergy to reestablish that breakdown potential if the arc is blown out.The arc may need to be reestablished a number of times during theignition period. As the gasses of the charge pass through the ignitiongap, successful ignition of the overall charge takes place through theignition of contiguous opportunities until there is a critical yield ofcombustion energy where massive propagation of the flame can beinitiated. When these ignition source requirements are met, the highturbulent charge can greatly assist in increasing the probability of asuccessful, fast and more complete charge burn.

Control of the volumetric charging, swirl, retained heat, variablecompression-expansion ratio, and appropriate control of ignition timingworking in conjunction with the engine RPM and controlled fuel-airmixture and the cylinder pressure versus time pattern peaking and shapecan greatly extend the lean burn limit and the usefulness of lean burn.As previously mentioned, in the present day cam operated valved engines,the fuel and ignition time are relatively well controlled however, withall of the special advantages that the computer control of the enginevalves makes possible, special improvements are needed in fuel-air andignition management to fully realize the overall synergistic effect.

In copending U.S. patent application Ser. No. 021,195 entitledELECTROMAGNETIC VALVE ACTUATOR, filed Mar. 3, 1987 in the name ofWilliam E. Richeson and assigned to the assignee of the presentapplication, now U.S. Pat. No. 4,794,890, there is disclosed a valveactuator which has permanent magnet latching at the open and closedpositions. Electromagnetic repulsion may be employed to cause the valveto move from one position to the other. Several damping and energyrecovery schemes are also included.

In copending U.S. application Ser. No. 07/153,257, entitled PNEUMATICELECTRONIC VALVE ACTUATOR, filed Feb. 8, 1988 in the names of William E.Richeson and Frederick L. Erickson and assigned to the assignee of thepresent application, now U.S. Pat. No. 4,878,464, there is a somewhatsimilar valve actuating device which employs a release type mechanismrather than a repulsion scheme as in the previously identified copendingapplication. The disclosed device in this application is a trulypneumatically powered valve with high pressure air supply and controlvalving to use the air for both damping and as the primary motive force.This copending application also discloses different operating modesincluding delayed intake valve closure and a six stroke cycle mode ofoperation.

In copending U.S. application Ser. No. 07/153,155 filed Feb. 8, 1988 inthe names of William E. Richeson and Frederick L. Erickson, assigned tothe assignee of the present application and entitled PNEUMATICALLYPOWERED VALVE ACTUATOR, now U.S. Pat. No. 4,899,700, there is discloseda valve actuating device generally similar in overall operation to thepresent invention. One feature of this application is that controlvalves and latching plates have been separated from the primary workingpiston to provide both lower latching forces and reduced mass resultingin faster operating speeds.

The presently copending U.S. application Ser. No. 209,279 entitledPNEUMATIC ACTUATOR WITH PERMANENT MAGNET CONTROL VALVE LATCHING, nowU.S. Pat. No. 4,852,528, and U.S. patent Ser. No. 209,273 entitledPNEUMATIC ACTUATOR WITH SOLENOID OPERATED CONTROL VALVES, now U.S. Pat.No. 4,873,948, both filed in the names of William E. Richeson andFrederick L. Erickson on Jun. 20, 1988 and assigned to the assignee ofthe present invention address, among other things, improvements inoperating efficiency over the above noted devices.

Other related applications all assigned to the assignee of the presentinvention and filed in the name of William E. Richeson on Feb. 8, 1988are U.S. patent Ser. No. 07/153,262 entitled POTENTIAL-MAGNETIC ENERGYDRIVEN VALVE MECHANISM, now U.S. Pat. No. 4,883,025, where energy isstored from one valve motion to power the next, and U.S. patent Ser. No.07/153,154 entitled REPULSION ACTUATED POTENTIAL ENERGY DRIVEN VALVEMECHANISM, now U.S. Pat. No. 4,831,973, wherein a spring (or pneumaticequivalent) functions both as a damping device and as an energy storagedevice ready to supply part of the accelerating force to aid the nexttransition from one position to the other.

U.S. Pat. Nos. 4,109,630 and 4,373,486 assigned to the assignee of thepresent invention disclose improved and easily controlled breakerlessignition systems suitable for utilization in conjunction with thepresent invention. The entire disclosures of all of these copendingapplications and the aforementioned issued patents are specificallyincorporated herein by reference.

The availability of fast acting and easily controlled valve actuatingmechanisms such as those disclosed in the abovementioned copendingapplications makes possible a more complete and efficient overallvehicle operation management than was heretofor possible.

Among the several objects of the present invention may be noted theprovision of an operator controlled vehicle drive train which iseffective to maximize the operating economy of a vehicle using a sparkignited internal combustion engine, to maximize the performance and thegeneral transient and steady state vehicle drivability, and to minimizeharmful engine emissions without the use of catalytic converters and tooptimally affect economy and performance the provision of a morecomprehensive computer control of vehicle operating parameters; theprovision of a vehicle management system which takes full advantage offast acting and highly controllable intake and exhaust valve mechanisms;the provision of a vehicle management computer which controls air-fuel,ignition and valving of an engine using a stored steady state table ormap of engine information, currently modifies that information accordingto dynamic vehicle behavior, and optimizes that information on a longterm basis in accordance with average long term vehicle behavior: theprovision of vehicle control which allows the vehicle engine to beoperated in each of several different modes; the provision of a vehiclemanagement computer according to the previous object which may operateon an individual cylinder basis; and the provision of a vehicle controlin accordance with the previous object which includes two-stroke cycleand six-stroke cycle modes. These as well as other objects andadvantageous features of the present invention will be in part apparentand in part pointed out hereinafter.

In general, a vehicle management system has an arrangement for sensing aplurality of current vehicle performance indicators, environmentalconditions and driver input, and a computing system which is responsiveto the sensed input information to determine a plurality of vehicleoperating parameters. The computing system includes a microprocessor,and a read only memory including a look-up table of optimum engineoperating parameters under a wide variety of engine performanceconditions. Controls are actuated by the computing system forcontrolling the vehicle in accordance with the determined parameters.

Also in general and in one form of the invention, an electronicallycontrolled valve actuating mechanism and an associated intake valve on areciprocating piston four stroke cycle internal combustion engine arecontrolled to operate selectively in a first mode at lower enginespeeds, a second mode at higher engine speeds, and a third mode at nearmaximum engine speeds. The first mode includes increasing the portion ofthe cycle during which the intake valve is open as the engine speedincreases the second mode includes decreasing the portion of the cycleduring which the intake valve is open as the engine speed increases, andthe third mode includes opening and closing the intake valve insynchronism with engine speed to operate the engine as a conventionalthrottled engine The engine may also be operated in a two-stroke cyclemode under high demand conditions and a lean burn mode under low demandconditions.

Still further in general, the present invention allows the conversion ofat least one and perhaps all of the cylinders of the engine to a leanburn mode of operation only during periods of low engine demand. Thelean burn mode includes the steps of closing an exhaust valve of theconverted cylinder before the piston of that cylinder reaches a top deadcenter position to retain exhaust gas in that cylinder, and thereafteropening an intake valve of the converted cylinder to admit fuel and airto be mixed with the retained exhaust gas, and subsequently compressedand ignited to obtain a power stroke from the piston of the convertedcylinder.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a over-all schematic diagram of a vehicle management computerillustrating the present invention in one form and illustrating apossible set of performance indicators;

FIG. 2 is a more detailed schematic diagram of the vehicle engineoperational processor of FIG. 1;

FIG. 3 is a more detailed schematic diagram of the valve control systemof FIG. 2, and, in particular, the steady state operational profile;

FIG. 4 is a more detailed schematic diagram of the valve control systemof FIG. 2, and, in particular, the corrective (command and delta)operational profile; and

FIG. 5 is a more detailed schematic diagram of the valve control systemof FIG. 2, and, in particular, the calibration operational profile.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawing.

The exemplifications set out herein illustrate a preferred embodiment ofthe invention in one form thereof and such exemplifications are not tobe construed as limiting the scope of the disclosure or the scope of theinvention in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawing generally, the vehicle management system isseen to sense a plurality of current vehicle performance indicators andenvironmental conditions such as individual engine cylinder peakpressure 43, air mass flow 45 into the engine, ambient air temperature47, ambient air pressure 49, ambient air relative humidity 51, engineintake manifold pressure 58, fuel temperature 55, vehicle speed 57,exhaust gas temperature 59, engine revolutions per minute 61, enginecoolant temperature 63, and engine crank shaft angle 65. Auxiliary powerrequirements such as air conditioner demand may be included as inputs.The system also senses a number of driver inputs such as the degree 41to which an accelerator pedal is depressed, the degree 67 to which abrake pedal is depressed, the octane rating of the particular fuel beingused as well as its stoichiometric point or other indication of theenergy content of the particular fuel 69, and a manual override 71 ofthe management system In response to this information, a plurality ofvehicle performance determining operating parameters such as engineignition timing 37, the duration and timing of opening and closing ofengine intake and exhaust valves 91, and the supply of fuel 93 and air95 to the engine are controlled in accordance with the environmental,performance and driver inputs. Fuel 93 and air 95 are shown separatelyin FIG. 1 to emphasize the fact that the present invention, whiledescribed in conjunction with a conventional spark ignited internalcombustion engine, is applicable to other engines such as Diesel enginesThe supercharger control 92 may enable an exhaust gas drivensupercharger of enhanced low speed effectiveness as will be describedlater A microprocessor, and a read only memory including a look-up tableof optimum engine operating parameters under a wide variety of engineperformance conditions are employed in the control process.

Referring more particularly to FIG. 1, the heart of the vehiclemanagement computer is the vehicle-engine operational processor 11,itself shown in greater detail in FIG. 2. The processor 11 receivesenvironmental conditions, such as barometric pressure 49; vehicleperformance indicators, such as vehicle velocity 57; operator inputs 13,such as accelerator pedal position 41; and engine performanceindicators, such as crank shaft angle 65 as inputs and provides a numberof operating parameter outputs such as ignition timing control 37 aswell as a display 15 of the current status of a number of the inputindicators. The operator inputs and some of the vehicle performanceindicators determine the vehicle operational profile 17. The systemgenerally operates in an open loop fashion with closed loop operationbeing only occasionally used during times of near steady state operationas during cruise.

The several condition sensors employed in the present invention are perse known, generally analog devices. In FIG. 2, these inputs first passthrough an analog to digital converter 19 which, in conjunction withinput port 21 which may directly receive further digital inputs,functions to supply input information on a time sequenced basis to themain bus 23. Thus, each digital input indicator has its own unique timeslot as defined by a central processing unit or CPU 25. Bus 23 providestwo way communication between the central processing unit 25, a randomaccess memory 27, a read-only memory 29 and a test and setup port 31 forexternal access to the system. Bus 23 also provides one-waycommunication by way of the output port 33 for controlling the engineparameters and providing the display 15 of FIG. 1 The function of theoperational processor of FIG. 2 under steady state conditions is shownin greater detail in FIG. 3.

In FIG. 3, a master clock 85 provides timing pulses to the centralprocessing unit 25 which in turn synchronizes operation of the othercomponents. Bi-directional communication between CPU 25 and steady stateread only memory 103, steady state random access memory 105, operatingrandom access memory 107, command random access memory 99, delta randomaccess memory 101 and a calibration random access memory 87 is all byway of bus 23. It will be understood that while the several randomaccess memories are depicted as separate, several or all may be portionsof a larger memory shown generally as 27. Similarly, the steady stateread only memory 103 and other read only memories to be discussed latermay be separate memories or portions of a larger shared read only memory29.

The steady state read only memory 103 stores a table or tables of engineoperating parameters. The table or tables are determined for aparticular make and model of vehicle, i.e., are factory determined. Forgiven values of the input environmental conditions, operator inputs andperformance indicators, a set of operating parameters is read frommemory 103 and stored in steady state random access memory 105 Theoperating parameter values stored in memory 105 are modified asnecessary in accordance with the information in the delta random accessmemory 101 and in the command random access memory 99 and the values asthus modified are stored in operating random access memory 107 forcurrent engine control. Particular engine operating parameters are readfrom the operating memory 107 and sent to the output port 38 which mayinclude shift registers 107 and 109 with gated outputs and a counterduration generator 111 for fuel injection and from there are used toappropriately actuate the pertaining driver such as ignition driver 75.

Regardless of the actual way in which the tabular data for a particularvehicle and engine is stored in memory 103, the information may bethought of as several independent n-dimensional vector spaces where eachdimension corresponds to a particular performance indicator, operatorinput, or environmental condition and the value of a vector in aparticular space as determined by the values of each of its dimensionscorresponds to a particular vehicle operating parameter. The informationmay also be thought of as a single n+1 dimensional vector space or arraywith the n dimensions again corresponding to the input information andthe additional dimension serving to identify the particular operatingparameter such as ignition time or intake valve opening time.

Cylinder to cylinder variations are one major problem in controllingemissions and maximizing economy. These are due to non-identical air andfuel ingestion, differences in compression ratio and other variations.If the approach to emission control is to run lean burn, the most leancylinder may be operated near its lean burn limit close to misfire whichwould greatly increase emissions. To avoid misfire, the most leancylinder would be run slightly more rich than its lean burn limit Underthese circumstances, depending on the variation between cylinders, themost richly operating cylinder may be too rich. Increasing the dimensionof the vector space by one allows for storage of a plurality ofdifferent valve actuation time determining values and selection of thevalue for a particular valve best suited to the current operatingtraits. In this case the current engine operating traits should includetraits indigenous to individual ones of the engine cylinders, such aspeak cylinder pressure 48. As an alternative, an offset or correctionfactor could be computed for each cylinder and applied to the valueyielded by the table. Of course, the other cylinder parameters such asignition timing may also be individually controlled.

It will be recognized that these tables can consume considerable spacein the RAM 27 and ROM 29. Efficient utilization of memory may dictatethat n be reduced, i.e., that some of the less important environmentalor performance indicators be omitted. Memory may also be conserved byrange encoding the particular inputs. For example, the values of thevector dimension corresponding to engine RPM could be the integers fromone to 7 with one corresponding to the range from idle to 1200 RPM, twocorresponding to 1200-1600 RPM, and successive integers assigned to eachinterval of 400 RPM up to seven which would indicate over 3200 RPM. Suchrange encoding of any of the inputs is a balancing of accuracy againstmemory space and speed of the table look-up operation.

The n inputs are not necessarily independent, that is, certain ones maybe computed from others. Vehicle acceleration 113 of FIG. 1, forexample, may be computed from timed repeated samplings of velocity 57rather than directly measured. In some cases, this is dictated by thenature of the transducer used to sense the input condition. As oneexample, reasonably priced present day sensors for determining oxygencontent in the exhaust (input line 39) are too slow acting for rapidchanges in engine demand situations and therefore that input is not usedin FIG. 4. These sensors are, however, adequate for long term updatingof the system and therefore used in the long term "tuning" of the engineas in FIG. 5. Of course, for any particular engine-vehicle installationcertain of the inputs may be omitted, while for other inputs, it may beimportant to sense not only the input value, but also its rate ofchange. As an example of the latter, one of the n inputs 41 isaccelerator pedal position, but for rapid modification of the engineoperating parameters, it may be desirable to know not only that theoperator has depressed the pedal, but also that it was depressed rapidly(the first derivative of pedal position) as in emergency passing ofanother vehicle. It may also be desirable to know that the pedal wasdepressed rapidly initially and then more slowly later on (the secondderivative of pedal position with respect to time). The particularinputs used represent a trade off between ideal vehicle management andavailable memory space along with other economic considerations.

FIG. 4 shows the sources of corrective measures to be placed in thedelta random access memory 101 to modify the fuel, ignition and valvecontrol information found in the steady state read only memory 103 andthen stored in the operating random access memory 107. The instructionsin the read only memory 115 are for a given RPM, and effective torqueproduced by the engine when operating at a given engine coolanttemperature; inlet air temperature, barometric pressure and relativehumidity; and other engine operating traits or conditions. When theseconditions change, the information read from read only memory 115 ismodified accordingly and stored in delta random access memory 101 andthen transferred to the current operating information random accessmemory 107 and used for engine control. Such modifications are generallyspeaking to account for changes in the environment of the vehicle

An indication of the indicated mean effective pressure and RPM 61 areused to control the required fuel and the derived ignition time Oneapproach is to measure air mass flow 45 directly, or to measure thebarometric pressure 49, temperature 47 and intake manifold pressure 53and then compute the indicated mean effective pressure (withoutcombustion). In either case, corrections should be made taking therelative humidity 51 into consideration. In order to control the fueldriver 71, the fuel temperature 55 and fuel octane 69 should beconsidered Another approach is to measure engine shaft torque 73, and astill further approach is to set the air to fuel ratio based on the useof an oxygen sensor measuring the oxygen content 39 of the exhaust. Eachof these approaches works well under steady state conditions, althougheach has its own limitations.

Under conditions of suddenly increasing loads, the already difficult tointerpret pulsating intake manifold pressure 53 with its reversing flowpulses becomes even more difficult to filter and evaluate. This resultsin significant delays in determining the required spark (37) advance anddetermining the required fuel to control (111) the fuel to air ratio atthe proper enriched operating point. If an air mass flow sensor 45 isused, the slow response time creates significant measurement and controlproblems. These inputs are useful for long term or slow updating of thetables, but for rapid response, if the engine torque 73 and RPM 61 areknown, then the position, change in position, rate of change of positionand the acceleration of the rate of change of position of theaccelerator pedal provides immediate useful information for transitionoperation. The transition response of the engine is also affected by thestatus of the transmission 97 and the kinetic energy of the vehiclewhich is proportional to the square of the velocity 57.

FIG. 2 illustrates a number of alternative vehicle traits and otherinput information which may be used in the control of the engine. Thecylinder peak pressure 43, the time 77 at which that peak pressureoccurs, and the burn time 79 may all be measured using a cylinderpressure sensor. Thus, while shown as three separate inputs 43, 77 and79, the actual input may be from pressure sensors in one or more of thecylinders which are periodically sampled and the information computedtherefrom. This same principle may be applied to other inputs such asthe accelerator pedal position and its several derivatives discussedabove. An ionization (flame conduction) sensor in a cylinder can alsoprovide a measure of burn time 79, however, this measure is sometimesdifficult to obtain under all engine operating conditions. Engine torque73 can also be measured directly, however, this and cylinder pressuresensors are, at the present time, relatively expensive. Exhaust oxygensensors 39 are commercially available and work relatively well, but theymust be up to near steady state operating temperature before validresults are obtained. They have a slow time response and are alsosubject to aging causing inaccurate indications. Exhaust gas temperatureis quite useful as an indication of engine operating efficiency, butthese and some of the other sensors possess relatively long timeconstants and are most useful in long term adjustment of the operatingcharacteristics of the engine. To avoid these long time constantproblems, the present system operates the engine based on theinformation in the steady state ROM 103 as updated (see FIG. 5) orcalibrated in the calibration RAM 87. Immediate or short term changes inthe engine operational requirements are effected primarily by theportion of the system depicted in FIG. 4.

The delta ROM 115 of FIG. 4 is a factory set map of appropriateresponses to operator indicated changes such as depression of theaccelerator or brake pedal for given current operating conditions. Itmay, of course, be a portion of the general ROM 29 of FIG. 2. This mapor table is transferred to and updated in delta RAM 101 which may be aportion of the general RAM 27 of FIG. 2 which provides the currentoperating information.

Part of the delta RAM information has to do with selection of certainvehicle negative accelerations where decisions are made to use less thanthe full complement of cylinders of the engine for power. The cylindersnot used are put into adiabatic no fuel operation. This condition issignaled by the operator backing off the accelerator pedal and/or,later, operation of the brake pedal progressively placing the engineinto an energy absorbing air compressor mode. Removing pressure on thebrake pedal and depression of the accelerator progressively puts theengine back into a power mode. When the same pattern of variationsoccurs during operation as it did during the original mapping, the deltaRAM 101 corrections are applied to the steady state RAM 105. Again, RAM105 may be a portion of the general RAM 27.

In addition to the brake 67 and accelerator 41 positions, the circuit ofFIG. 4 is controlled by RPM and perhaps other measures supplied by thesteady state circuit of FIG. 3 and stored in command RAM 99 and theother inputs illustrated in FIG. 4. As noted earlier, the severalderivatives of pedal positions may be measured by periodic sampling ofthe inputs on lines 41 and 67.

A test and set-up port 81 is shown in FIGS. 2 and 3. This port allowsdata and command access to the main bus 23 so that operational tests maybe performed and data can be entered into the EPROM 81 and inparticular, the CAL EPROM 83 of FIG. 5.

The calibration computer of FIG. 5 obtains sensor data such as shown inFIG. 2 and, in the preferred realization, the data shown in FIGS. 3 and4. The other data line 85 may include a variety of overall performancemeasures such as exhaust oxygen 39, exhaust gas temperature 59, knocksensing 89, flame rate, combustion chamber ionization measures, peakpressure time 77, or burn time 79. These measurements typically havelong time constants or variations which require averaging either ofwhich entails delay and causes difficulties in direct real timeutilization of the measurements to control an engine One problem hasbeen that the desired vehicle dynamic responses are fast while the timeresponses of these sensors are slow and surging or oscillation has beenvery difficult to control. To avoid such problems, the approach of thepresent invention utilizes the calibration computer of FIG. 5 toclassify various dynamic states, measure the mean responses of the deltaand steady state controls, and to determine from over all performancedata in EPROM 83 what recalibrations are necessary. These recalibrationsare created slowly, stored in calibration RAM 87 and periodicallytransferred to the steady state operating RAM 107 to modify the controlof the engine. Thus, the system slowly converges to an individualengine's optimum ignition timing air to fuel ratio, and valve timing. Inthe main, however, valve control mapping will be relatively stationaryin its profile depending on engine RPM and torque for a given engine.Aircraft applications, for example, might employ a different map toaccommodate engine temperature excursions and altitude variations alongwith different performance demands during take-off, climb and cruise.Such engine operation optimization in response to a set of requirementsin conjunction with other conditions can be used to optimize operationof an engine for a variety of applications such as trucking, boating andother mobile or fixed engine environments.

There are a number of ways that the approximately correct amount of fuelcan be determined and added to the intake air of an automobile engine togenerally get satisfactory drivability when the vehicle is under heavyacceleration, is operated under general driving conditions, or isoperated in cruise conditions. The main problem is to get very goodvehicle drivability or engine operation under all of the static anddynamic operating conditions and yet maximize economy and minimizeemissions The main root of the problem is in the long time constants insensing the intake air mass flow rate so that the fuel can be properlyadjusted. Instead of using a throttled manifold engine with variable airdensities, sensing problems and pumping losses an unthrottled variablevalve engine can be used and the air consumed can be more rapidly andaccurately determined.

The options and advantages of the vehicle management system are nowfeasible at least in part because of the reduced valve throttlinglosses, the reduced heating of the exhaust valve, the separate controlof opening and closing times, and valve timing optimization to controlas well as maximize engine output and efficiency. In the region ofoverlap of present valving systems there is an exchange of gas from theexhaust port to the intake manifold due in large measure to the lowpressure of the intake manifold causing, in part, heating of the intakevalve and affecting, among other things, fuel evaporation whichcontributes to deposit buildup on the intake valve. This affects enginerespiration and can reduce volumetric efficiency. The present inventiontimes and controls rapidly operating, low throttling valves so thatvalve overlap may be less often used greatly improving this situation.When overlap is not used, fuel enrichment can be eliminated. Rapid valveoperation will give rise to reduced pumping losses, increased volumetricefficiency, and allow for controlling the expansion ratio of the enginepower stroke. In particular, instead of controlling the engine bythrottling the intake manifold thereby operating the engine in a vacuumpump or variable intake density mode, the engine, and in particular thecylinder charge, may be controlled by governing the duration of time theintake valve is open followed by an adiabatic expansion and compression,or by controlling the net time during the cycle that the intake valve isopen as opposed to throttling the intake to the engine.

Opening the intake valve at a controlled time (dependent on patterns ofvehicle performance and other indicators) such as in the order of 10 to70 degrees after top dead center and closing at the appropriate timeincreases volumetric efficiency and prevents mixing of exhaust andintake gases which mixing is characteristic of conventionally valvedengines during the traditional valve overlap periods.

Closing the intake valve at a precise point in the cycle will increaselow engine speed torque by stopping the reverse flow of the intakemixture back into the intake manifold which occurs in conventionallyvalved engines at low RPM. Elimination of this exchange of gasses willhave a highly desirable impact on operation of the engine such asallowing low speed operation of the engine with higher volumetricefficiency as well as greatly improving the starting and low temperatureengine operation. The controlled sudden opening of the intake valve isadvantageous in increasing and controlling turbulence and improving themixing of fuel and air during the charging cycle. At low engine speeds,more turbulence is needed for fast burns whereas at higher engine RPMhigher turbulence would only serve to increase heat losses, hence, theturbulence support should be varied. This turbulence concept is alsoapplicable to Diesel engines especially during low speed, high torqueoperation where lack of proper burning creates smoke and particulatepollution. High turbulence under these conditions greatly improvesengine performance. More rapid opening of the exhaust valve will reducethe heretofore necessary lead time in starting exhaust blow down in theexpansion stroke. The later opening of the exhaust valve extends thepower stroke, reduces carbon monoxide and hydrocarbon emissions due tolessened quenching, and reduces pumping losses as well as loweringexhaust gas temperature The rapid opening of the exhaust valve nearbottom dead center also creates mass flow effects which yield recoveredenergy in the crank shaft by a subatmospheric exhaust gas ventingstroke. Exhaust gas driven superchargers are known, but are ineffectiveat lower engine speeds. Such an exhaust gas driven supercharger may beused in conjunction with the present invention to provide low speed,high torque operation. For example, in the case of a combustion ignitedinternal combustion engine, a rapid opening and/or an early opening ofthe exhaust valve significantly enhances supercharger response at lowspeed operation. With either spark ignited or compression ignitedinternal combustion engines, the exhaust valve may be opened earlier atany engine speed to shorten the time required for intake air pressureboost from the exhaust gas operated supercharger. When rapid attack, lowspeed manifold boost along with late opening of the intake valve isused, cylinder turbulence can be increased to enhance clean burningunder high fuel injection levels The more rapid the opening and closingof the exhaust and intake valves, the higher the fluidynamic resonance Qfactor, which will control and increase volumetric efficiency throughoutthe engine's operating range. Improvement in the volumetric efficiencyof air compressors under variable operating circumstances is alsopossible with such intake and exhaust valve arrangements The more rapidopening of the exhaust valve in the internal combustion engine, withless throttling and the reduction of the peak velocity of the boundarylayer of the hot gasses past the valve will reduce heat transfer fromthe exhaust gases to the valve allowing the valve to run cooler,improving valve life particularly under highly oxidizing lean burn, highpower and high temperature conditions. When used in conjunction with anexhaust gas driven supercharger, more exhaust gas energy can berecovered to increase supercharger output. The reduced exhaust gasquenching will reduce unburned hydrocarbon and carbon monoxideconcentration in the exhaust.

The exhaust gases that are normally emitted near the end of the exhauststroke are rich in unburned hydrocarbons due to scavenging effects ofthe unburned boundary layers close to the cooler combustion chamberwalls and the boiling of unburned hydrocarbons out of cavities such asaround the head gasket and around the piston and its compression ringsthat were deposited there due to pressurization of the charge due to thecompression stroke and burning charge pressurization. Rapid closing ofthe exhaust valve will retain more of these emission rich gases forreburning and the control of exhaust valve opening that controls theexpansion ratio of the engine will go toward greatly reducing oreliminating the need for the catalytic converter The use of controlledexhaust gas retention can also eliminate the present exhaust gasrecirculating devices.

Precise differential electronic control of the opening and closing timesof the valves allows a control of the mass flow through the intake andexhaust valves in various operating modes with a resulting reduction ofundesirable emissions, increase in volumetric efficiency and generallyallows an optimization of engine performance. Differential control ofignition and fuel can allow all cylinders to be essentially identicalthereby allowing a closer approach to the lean burn limit or to othercritical points. Such precise electronic control can facilitate a numberof further modifications including the fact that all cylinders may bepurged with fresh air during shut down and that all valves may be closedwhen the engine is not in use thereby eliminating exposure to theatmosphere and reducing corrosion within the combustion chambers due toresidual gasses condensates and oxides of nitrogen.

Initial cranking to start the engine may be performed with appropriatevalves maintained open until cranking speed is sufficiently high. Thisprovides a "compressionless" cranking to aid cold weather starting. Coldengine starting and running during the warm-up period without consumingexcessive fuel is made possible by 6-cycle operation where oneadditional compression and expansion are used to vaporize the fuel. Thisapproach will greatly assist in the use of low volatility (low Reedvapor pressure) fuels that are safer and provide less evaporation to theatmosphere. This 6-cycle mode of operation is described in greaterdetail in the abovementioned U.S. patent Ser. No. 153,257 PNEUMATICELECTRONIC VALVE ACTUATOR, now U.S. Pat. No. 4,878,464. This facilitatescold engine starting with the present fuels and the future lowvolatility fuels and cold engine running as well as reducing unburnedhydrocarbon emission prior to the time when a catalytic converter can belighted. Such converters are ineffective until they reach an elevatedoperating temperature. Emission of unburned hydrocarbons from enginestart-up and coming up to temperature will be greatly reduced. Leavingthe cylinders of an up to temperature engine in appropriately chargedstates coupled with proper introduction of ignition spark, allows theengine to be restarted without cranking when the engine has been stoppedfor a short time period, such as sitting at a stop light.

Control of the number of cylinders in use, as during steady state cruseon a highway, or other low demand condition allows the active cylindersto be operated more efficiently because of the superior entropy due tohigher burn pressures and temperatures that are required to get thedemanded power level. Leaner burns can be used on the remainingcylinders due to the higher pressures and temperatures allowing higherignitability and higher propensity of burning of the charge.

Reduction of unburned hydrocarbon emissions during deceleration is alsopossible. Conventionally valved engines develop high intake manifoldvacuum during deceleration which enhances fuel evaporation on themanifold inner surface resulting in an overly rich mixture being burned.In particular, charging of the cylinders is controlled in the presentinvention by intake valve openings and closings and the intake manifoldis not under variable vacuum and hence does not exhibit the sameeffects. Further, the overly rich low density cylinder charge in theconventional engine may not ignite or burn as completely as it doesunder higher charge levels, hence, causing high unburned hydrocarbonemissions. Engines equipped with the present electronically controllablevalve arrangement may be used to aid normal or rapid deceleration byclosing selected valves for operation using fewer than the fullcomplement of cylinders or no powered cylinders allowing for vehicleslow down due to the rolling friction and aerodynamic losses underconditions where engine output is selectively less that the frictionallosses, or cause the engine to absorb power in an air compressor mode.

When spark, fuel and valving are controlled, heat recovery bycontrolling air intake temperature is facilitated. For example, highheat recovery may be used when the combustion temperature is low as whenoperating the engine well below maximum torque. Such heat recovery mayalso help control combustibility under lean or high exhaust gasretention conditions. Ideally, the combustion temperature would be heldto a predetermined maximum where one would have the best entropyposition but yet controlled NOX production.

Reduced hydrocarbon emission results from higher expansion ratio, lessquenching at the exhaust valve, reduced exhaust gas blow-down time,lower emission a& the end of the exhaust stroke as well as duringdeceleration, and generally less valve overlap operation as well as leanburn and programming the engine to use fewer than the full complement ofcylinders when possible. These combine to greatly reduce the need forcatalytic converters. General improvement in efficiency may be achievedby increased and controllable expansion of the power stroke gasesresulting, in part, from the very rapid opening of the present valvearrangement. The conventional exhaust valve may begin to open at 45 to80 degrees before bottom dead center (for a 0.01 inch seat clearance)and at 60 or more psi gas pressure in order to achieve the momentum ofthe gas mass necessary to evacuate the exhaust gases against a greatdeal of exhaust gas valve port throttling. The valve of the presentinvention may be opened at near bottom dead center to utilize more ofthe expansion during the power stroke. The conventional engine exhaustvalve may close 45 degrees after top dead center with the correspondingintake valve opening 20 to 40 degrees before top dead center resultingin perhaps 70 degrees of overlap where charge diluting exhaust is pulledinto the intake manifold and then back into the cylinder resulting incharge heterogeneity and hence lean burn ignitability and burningproblems. With the present invention, there is, in general, no suchoverlap between the intake and exhaust valves and hence there are lessproblems with developing heterogeneous charges and extending the leanburn limit.

The full control of the opening and closing of the valves of areciprocating engine allows for a design that has a basic controllablehigh expansion ratio under normal operation and can effectively changethat expansion ratio to allow for the same cylinder charge mass when thetemperature of the charge varies. In order to take the greatestadvantage of high expansion ratios, an engine of longer stroke for thesame bore and end combustion chamber volume may be utilized, and/orcomplementary supercharging may be used. This makes it possible torecover heat from the exhaust making trade offs of higher efficiency dueto lower entropy of the higher burn temperatures against the productionof NOX due to these higher temperatures and the increased efficiencyderived from higher expansion ratios. It should also be noted that afast burn, long stroke, high speed engine with reduced maximumtemperatures and dwell time at those temperatures reduces NOX emission.

Opening of the exhaust valve should usually occur when the pressure inthe cylinder is nearly the same as the pressure in the exhaust port(generally atmospheric or crankcase pressure). Exhaust valve opening atother times reduces engine efficiency and increases undesirableemissions by purging unburned hydrocarbons from the cylinder. This nearzero pressure differential exhaust valve opening time depends upon thecurrent engine status.

The modes of operation shown in FIGS. 11 and 12 of the aforementionedcopending U.S. patent application Ser. No. 153,257 as well as six-strokecycle, two-stroke cycle, and operation as a conventional throttledengine are available under the computer control of the presentinvention. Those two modes may both take advantage of operation of theintake manifold at or near atmospheric pressure thereby significantlyreducing the pumping losses associated with conventional throttledengines FIG. 12, as opposed to FIG. 11 of that copending application,shows a technique which allows for lower valve opening and closingvelocities. The power consumed by a valve mechanism is directlyproportional to the square of the effective valve velocity or inverselyproportional to the square of the valve transition time with appropriateallowance being made for acceleration and deceleration.

Valve operation in mode 1 as depicted in FIG. 11 of that copendingapplication may be used at comparatively low speeds when the duration ofvalve operation (the time the valve remains open or closed) issufficiently long compared to the time required to actuate or move thevalve from one position to the other. At higher engine RPM, the enginemay be switched over to mode 2. It will be noted that, in mode 1, theportion of the cycle during which the intake valve is open increases asengine speed increases while in mode 2, the portion of the cycle duringwhich the intake valve is open decreases with increasing engine speed.

On starting, mode 2 has a highly desirable feature of treating the fuelto a more turbulent experience and, hence, is superior to mode 1 inevaporating and homogenizing the fuel in the air/fuel charge for coldstarting. Cranking of the engine may also take place with the exhaustvalve kept open and the intake valve kept closed (or with the exhaustvalve kept closed and the intake valve kept open) to take advantage ofengine momentum to help engine starting when the valves are suddenlyproperly sequenced. Such delayed valve operation starting may be ineither mode I or mode 2 and may use delayed input valve opening todevelop high velocity and turbulent air/fuel mixture flow with itsassociated improved evaporation and mixing of the air/fuel charge.

It is also possible to keep both intake and exhaust valves closed withignition held in abeyance to allow a vehicle or load to motor an enginein an adiabatic way for conditions where no positive torque is required.For increased slow down (i.e., for absorbing shaft energy) where avariable negative torque is required, the nonfueled, nonignited enginecan have the valves appropriately timed and be effectively used forbraking.

Still referring to Copending U.S. patent application Ser. No. 153,257,the sooner the valve closes after bottom dead center, the greater willbe the retained ingested charge into the engine and, hence, the greaterthe engine's torque. The primary difference in the two modes ofoperation is that there are operating circumstances, such as at high RPMand low torque, where the mode 1 operation requires a valve to closevery soon after having opened. In mode 2, the period of time betweenopening and closing is always at least 180 degrees of crankshaftrotation as compared to perhaps as low as 30 degrees of crankshaftrotation in mode 1. Hence, mode 1 may require extremely fast opening andclosing times. The increase in energy required to effect these rapidvalve responses is disproportionately high. For example, to operate thevalve 180/30=6 times as fast requires approximately the square or 36times as much energy. Operating the valves in mode 2 requires far lessenergy and has other desirable characteristics.

In addition to modes 1 and 2 as set forth in the above copendingapplication, the versatile control of the present invention allowsfurther modes of operation including opening and closing the intakevalve in synchronism with engine speed to operate the engine as aconventional throttled engine, or temporary operation as a two strokecycle engine Such a two stroke cycle mode of operation is known as"harmonic induction" with the exhaust valve opening slightly prior tobottom dead center and remaining open until slightly after bottom deadcenter whereupon the exhaust valve closes and the intake valve opens fora short period followed by closing of the intake valve and compressionfor the remainder of the cycle. The control also provides for a methodof starting and accelerating a vehicle through a range of vehicle speedsduring which the vehicle internal combustion engine is operatedselectively in a plurality of different operating modes. According tothe method, cranking of the engine may be accomplished in acompressionless mode preparatory to starting the engine, the engine maybe run in a second mode at a relatively low speed for a warn-up intervalas a six-stroke cycle engine where each engine cylinder cycle includesan essentially adiabatic compression and expansion. The highervolumetric efficiency with the valving opening and closing at top andbottom dead center along with the additional strokes allows coldstarting with reduced vapor pressure fuels. Thereafter, the computer mayeffect a conversion to a third mode of operation as a four-stroke cycleengine during normal engine operation. This third mode may include modes1 and 2 of the above described copending application Increasing theengine speed and converting to operation in a fourth mode as atwo-stroke cycle engine, or operation as a conventional throttled engineunder high demand conditions is also possible

The six-stroke cycle mode of operation has extra compression andexpansion strokes after the intake and compression of a four-cycle mode.The purpose of this extra revolution of the crankshaft is to evaporateand more thoroughly mix the fuel and air so that cold start and run cantake place without the presently used automatic choke or specialextensive fuel enrichment This leads to better cold starting and coldrunning without causing the extensive unburned hydrocarbon emissions ofthe present day engines which now occur prior to the time the catalyticconverter comes up to temperature. When the engine warms up somewhat,conversion may be made to any of several four-stroke cycle modes. Forexample, the intake valve may be opened at a preferred time and theclosing time controlled to thereby control the quantity of the ingestedcharge. This closing may take place prior to or slightly after bottomdead center (mode 1) or well after bottom dead center but prior to topdead center (mode 2).

Controlling the closing time of the exhaust valves may also be used tocontrol the fuel/air mixture either separately or in conjunction withcontrolled intake valve opening and closing as in the previous examples.If the exhaust valve closes prior to top dead center, retained exhaustgas will be placed in an adiabatic compression and subsequent adiabaticexpansion prior to the time the intake valve opens. The time at whichthe exhaust valve closes controls the volume of retained exhaust gas andtherefore also controls the volume if ingested fuel and air when theintake valve opens as well as the retained heat in the cylinder. Thecapability to control retained heat can aid in lean burning. Lean burnsburn slowly and to get the most useful burn at a given RPM the ignitionshould take place at an early time during the compression stroke.Successful ignition depends on the air/fuel mix and the density andtemperature of the ignition plasma. Retained exhaust gas gives a highertemperature and pressure for a given ignition time in the cycle with ahigher probability of ignition and flame propagation through thesurrounding gas. This can within certain limits greatly extend the leanburn limits and can be used to reduce emissions. Due to the earlierignition and higher temperature of the cylinder gas before ignition,more thorough burning can take place which will reduce unburnedhydrocarbon and carbon monoxide emissions. The lower energy yield of thecylinder gas reduces the maximum burn temperature which in turn reducesNOX emissions.

In the operation of a four cylinder engine, there is a companioncylinder operating 180 degrees of rotation behind a given cylinder sothat the excess air/fuel gases that are expelled by the given cylinderin mode 2 are taken in by the companion cylinder. An engine using thismode of operation would likely have a single central injection orcarburetion of fuel. This exchange of intake gasses within the intakemanifold more thoroughly mixes and evaporates the fuel and the coldstarting characteristics of the engine are much improved.

Another advantage of operating intake valves in mode 2 as compared tomode 1 is that finer control over the ingested charge is expected at allengine speeds. In mode 1, the minimum charge is controlled by the timeto open plus the time to close the intake valve. When the engine isoperating at a higher speed, this minimum time consumes greatercrankshaft angular rotation and the minimum charge may not be as low asdesired. The minimum charge is not controlled by the sum of theseopening and closing times in mode 2 and mode 2 allows for a full rangeof control over all engine speeds.

In the conventional cam operated poppet valve, the points in the enginecycle at which opening and closing commences is fixed, but the actualtime required for the valve to move between closed and open positionsdepends on engine speed. With the valve arrangement and control of thepresent invention, movement between closed and open positions is veryrapid and independent of engine speed, and the point in the cycle wheresuch opening or closing commences is selectable. These options allow forthe selective operation in the various modes discussed above and thosewhich follow.

Operating an internal combustion engine to control the turbulence of thegasses within at least one cylinder of the engine is possible by varyingthe time in the engine cycle at which an intake valve of the controlledcylinder is opened and, in particular, opening the intake valve earlierin the cycle at higher engine speeds and later in the cycle at lowerengine speeds. By monitoring certain engine performance traits andcorrecting the time at which the intake valve is opened, the system canminimize particle emissions in the engine exhaust.

Operation of the valves of individual cylinders of an internalcombustion engine over a range of engine speeds to optimize engineefficiency is possible by opening the exhaust valve of each cylinderduring the cylinder's expansion stroke at a time when the pressure inthe cylinder is near the pressure in its exhaust port. The valve isopened earlier in the stroke when the demand on the engine is low andlater in the stroke when the demand on the engine is higher. The valvesof individual cylinders of an internal combustion engine may be operatedover a range of engine speeds to optimize engine efficiency by ensuringthat the intake and exhaust valves of a common cylinder are not open atthe same time while the engine is operating at lower speeds and openingthe intake valve of each cylinder while the corresponding exhaust valveof that cylinder is still open at higher engine speeds. Higher and lowerspeeds as well as earlier and later in the stroke are relative termswith particular thresholds being design considerations for particularengines. When starting the engine, each intake valve is opened when thepiston of its cylinder is near top dead center and closed when thatpiston is near bottom dead center.

Control over one or more of the cylinders of a multiple piston internalcombustion engine is accomplished by storing a plurality of differentcylinder operation time determining values, monitoring a plurality ofcurrent engine operating traits including traits indigenous toindividual ones of the engine cylinders, selecting the value for aparticular cylinder best suited to the current operating traits, andcontrolling said particular cylinder at the time determined by theselected value. The time of ignition, fuel supply, and intake andexhaust valve opening and closing times for each cylinder may becontrolled to optimize performance while minimizing undesirable exhaustemissions.

At least one of the vehicle internal combustion engine cylinders may beoperated in a plurality of different operating modes to decelerate avehicle through a range of vehicle speeds by removing fuel supply to thecylinder for modest deceleration, maintaining the cylinder valves closedto operate the cylinder in an adiabatic mode for medium deceleration,and opening and closing the cylinder valves to operate the cylinder in anonadiabatic energy absorbing compressor mode for high deceleration.

Enhanced low engine speed operation of an exhaust gas actuatedsupercharger equipped engine may be achieved by opening the exhaustvalves of the engine when the associated cylinder pressure issignificantly above exhaust port pressure thereby releasing higherpressure exhaust gas to drive the supercharger.

The number of permutations of particular modes of operation for anengine are almost limitless. Furthermore, internal combustion engineshave been described in the preferred embodiment, but almost anyreciprocating piston device having at least one electronicallycontrollable valve actuating mechanism is suitable for practicing themethod of operating the electronically controlled valve actuatingmechanism and the associated valve by storing a plurality of differentvalve actuation time determining values, monitoring a plurality ofcurrent device operating traits, selecting the value best suited to thecurrent operating traits, and actuating the valve at the time determinedby the selected value.

From the foregoing, it is now apparent that a novel arrangement for theoverall management and control of a vehicle has been disclosed meetingthe objects and advantageous features set out hereinbefore as well asothers, and that numerous modifications as to the precise shapes,configurations and details may be made by those having ordinary skill inthe art without departing from the spirit of the invention or the scopethereof as set out by the claims which follow.

What is claimed is:
 1. A vehicle management system comprising:means forsensing a plurality of current vehicle performance indicators includingvehicle speed and engine crankshaft angle, environmental conditions, anddriver input including the degree to which the accelerator pedal isdepressed; means responsive to the means for sensing for determining aplurality of engine operating parameters including the duration andtiming of opening and closing of engine intake and exhaust vlaves, themeans for determining including a microprocessor, and a read only memoryincluding a look-up table of optimum engine operating parameters under awide variety of vehicle performance indicators, environmentalconditions, and driver inputs, the microprocessor being responsive tothe means for sensing to retrieve selected ones of the optimum engineoperating parameters from the read only memory and to modify theselected optimum engine operating parameters according to the currentsensed vehicle performance indicators, environmental conditions anddriver input; and means actuated by the responsive means subsequent tothe modification of the selected optimum engine operating parameters forcontrolling the vehicle in accordance with the modified optimum engineoperating parameters.
 2. The vehicle management system of claim 1wherein the plurality of performance indicators further includesindividual engine cylinder peak pressure, air mass flow into the engine,ambient air temperature, ambient air pressure, ambient air relativehumidity, engine intake manifold pressure, fuel temperature, exhaust gastemperature, exhaust gas pressure, engine revolutions per minute, andengine coolant temperature.
 3. The vehicle management system of claim 1wherein the driver input includes, the degree to which a brake pedal isdepressed, the octane rating and stoichiometric point of the particularfuel being used, and a manual override of the management system.
 4. Thevehicle management system of claim 1 wherein the plurality of vehicleoperating parameters includes the engine ignition timing, and the supplyof fuel and air to the engine.
 5. A vehicle management system for avehicle having a multi-cylinder engine, the system comprising:firststorage means for storing a fixed table of engine operating parameterscorresponding to various engine conditions; second storage means forstoring a table of engine operating parameters corresponding to variousengine conditions, the engine operating parameters including parametersunique to each individual engine cylinder, the second table beinginitially the same as the first table; means responsive to sensed engineconditions for modifying the parameters in the second table; and meansfor controlling the vehicle in accordance with the parameters stored inthe second table.
 6. The vehicle management system of claim 5 whereinthe first storage means comprises a read-only memory and the secondstorage means comprises a random access memory.
 7. The vehiclemanagement system of claim 5 wherein the means for modifying providesboth short term modification to accommodate dynamic changes int ehsensed engine conditions and long term modification to compensate forrelatively slow changes in the engine and the management system.